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硫铝酸盐水泥净浆半浸泡在碳酸钠溶液中的破坏机理
作者:刘赞群 候乐 邓德华 张丰燕 
单位:中南大学土木工程学院 长沙 410075 
关键词:碳酸钠 硫铝酸盐水泥 硫酸钠 盐结晶 化学侵蚀 
分类号:TQ 172
出版年,卷(期):页码:2017,45(5):639-643
DOI:10.14062/j.issn.0454-5648.2017.05.06
摘要:

 将水灰比为0.45硫铝酸盐水泥净浆试件半浸泡在装有10%Na2CO3溶液中的容器中,分别在(20±2) ℃,湿度(60±5)%的稳定环境中和循环变化条件下[先在(30±2) ℃、湿度(80±5)%的环境保持24 h、再在(20±2) ℃、湿度(60±5)%的环境保持24 h]研究其盐结晶破坏特征。结果表明:稳定环境下暴露72 d后,试件水分蒸发区表面出现了Na2SO4晶体,但并没有出现严重的盐结晶破坏;循环变化环境下,只经过4个循环8 d的侵蚀,试件水分蒸发区发生了严重的层状结晶破坏。其破坏机理是硫铝酸盐水泥水化产物与碳酸钠之间化学侵蚀生成物Na2SO4结晶破坏所致,并没有出现Na2CO3结晶破坏。如果胶凝材料水化产物与盐溶液之间存在化学反应,虽然环境条件满足盐结晶发生的要求,但化学侵蚀生成物结晶膨胀才是导致净浆或者混凝土试件水分蒸发区破坏的原因。

 

 Calcium sulphoaluminate (CSA) cement paste specimens were partially immersed in 10% Na2CO3 solution, under a constant condition (i.e., at 20 ℃ and 60 % RH) and a sharply fluctuating environment (i.e., firstly at 30 ℃ and 80% RH for 24 h, and then at 20 ℃ and 60% RH for 24 h), respectively. The results show that the specimens have little change in evaporation zone after 72-d exposure under the constant condition, but the specimens are severely damaged only after 4-cycle under fluctuated condition. The crystallization of Na2SO4 without Na2CO3 occurs, and Na2SO4 is a product of chemical reaction between Na2CO3 and CSA paste. The crystallization distress by the chemical attack product is due to the damage of evaporation zone of paste or concrete if there exists chemical reaction between the cementitious materials and salt solution.

 
基金项目:
国家自然科学基金(51378508)资助。
作者简介:
刘赞群(1975—),男,博士,教授。
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